The book starts out being neutral but then veers off into being biased on behalf of Leo Frank. There are better sources out there for information about the case.

Excellent sources of primary and secondary research about the Leo Frank Case include:

The Leo Frank Case Inside Story of Georgia's Greatest Murder Mystery 1913 - This is the first neutral book written about the murder of Mary Phagan and trial of Leo Frank.
WWW Link:
https://archive.org/details/TheLeoFrankCasemaryPhaganInsideStoryOfGeorgiasGreatestMurder

The Murder of Little Mary Phagan by Mary Phagan Kean Written by Mary Phagan Kean, the great grand niece of Mary Phagan. This semi-autobiographical and neutral account of the events surrounding the trial and appeals of Leo Frank include never before published detailed information about Frank's posthumous pardon. This insightful book is well worth reading and it's a refreshing change from the endless number of Jewish authored modern and contemporary books, disingenuously transforming the Leo Frank case into a neurotic, anti-Gentile, ethnoreligious-obsessed tabloid controversy.
WWW Link:
https://archive.org/details/TheMurderOfMaryPhaganByLeoFrankIn1913

American State Trials, volume X (1918) by John Davison Lawson tends to be biased in favor of Leo Frank and his legal defense team. This case commentary review provides an *abridged* version of the Brief of Evidence, leaving out some of the important testimony and evidence when it republishes parts of the trial testimony digest. Be sure to read the abridged closing arguments of Luther Zeigler Rosser, Reuben Rose Arnold, Frank Arthur Hooper and Hugh Manson Dorsey. For a more complete version of the Leo M. Frank trial testimony, read the 1913 Leo Frank Case Brief of Evidence and Atlanta's daily newspapers publishing the question and answer portions (July 28-August 21, 1913).
WWW Link:
https://archive.org/details/AmericanStateTrials1918VolumeXleoFrankAndMaryPhagan

Argument of Hugh M. Dorsey in the Trial of Leo Frank. Some but not all of the 9 hours of arguments given to the Jury at the end of the Leo Frank trial on August 22, 23, and 25, 1913. Only a dozen or so libraries in the United States have copies of this peroration in book format. This is an excellent book and required reading for students of the Leo Frank case to see how prosecutor Hugh Dorsey, in sales vernacular, 'closed' the panel of 13 men (the trial jury of 12 men plus Judge Leonard Strickland Roan).
WWW Link:
https://archive.org/details/ArgumentsOfHughM.DorseyInTheLeoFrankMurderTrial

The Leo Frank Trial Brief of Evidence (1913):

Leo M. Frank, Plaintiff in Error, vs. the State of Georgia, Defendant in Error. In Error from Fulton Superior Court at the July Term 1913, Brief of Evidence. Only a few original copies of this 300-page book-digest from 1913 and 1914 exist at the Georgia State Archive. This trial digest can also be found in the Leo Frank Georgia Supreme Court files.

Leo Frank's defenders often misrepresent these trial legal documents and examples can be found in the most popular books about the Leo Frank case by Steve Oney, Leonard Dinnerstein, Robert Seitz Frey, Elaine Marie Alphin, the Samueles' and other Frankites. Since the Leo Frank (BOE - brief of evidence) was released on the Internet, the number of books by pro-Frank extremists falsifying the trial testimony has diminished greatly.
WWW Link:
https://archive.org/details/LeoM.FrankPlaintiffInErrorVs.StateOfGeorgiaDefendantInError.In

Three Major Atlanta Dailies of the Time: The Atlanta Constitution, The Atlanta Journal and The Atlanta Georgian (Hearst's Tabloid Yellow Journalism). The most relevant issues concerning the murder investigation and trial are between April 28th to August 27th, 1913.

Atlanta Constitution daily newspaper: The Murder of Mary Phagan, Coroner's Inquest, Grand Jury, Investigation, Pre-Trial Discover, Trial, Appeals, Prison Shanking and Lynching reported about the Phagan-Frank Case in the Atlanta Constitution Daily Newspaper from 1913 to 1915.
WWW Link:
https://archive.org/details/LeoFrankCaseInTheAtlantaConstitutionNewspaper1913To1915

Atlanta Georgian daily newspaper (Lot's of Extras): covering the Leo Frank Case from late April through August 1913.
WWW Link:
https://archive.org/details/AtlantaGeorgianNewspaperAprilToAugust1913

Atlanta Journal daily newspaper (evening edition): April 28, 1913, through till the end of August, 1913, pertaining to articles about the Leo Frank Case.
WWW Link:
https://archive.org/details/AtlantaJournalApril281913toAugust311913

The most sensational criminal trial in Southern history concluded its testimony portion on August 21, 1913, a few days after Leo Frank made an admission on the witness stand (August 18, 1913) that some say amounted to a murder trial confession

On August 18, 1913, Leo Frank reveals the solution to the Mary Phagan murder mystery stating he might have "unconsciously" gone to the bathroom in the metal room to counter Monteen Stover's testimony that he was not in his inner or outer office from 12:05 to 12:10 PM on April 26, 1913:

Now gentlemen [of the Jury], to the best of my recollection from the time the whistle blew for twelve o’clock [noon on Saturday, April 26, 1913] until after a quarter to one [12:46 p.m.] when I went upstairs and spoke to Arthur White and Harry Denham [at the rear of the fourth floor], to the best of my recollection, I did not stir out of the inner office [at the front of the second floor]; but it is possible that in order to answer a call of nature or to urinate I may have gone to the toilet [in the metal room at the rear of the second floor]. Those are things that a man does unconsciously and cannot tell how many times nor when he does it (Leo Frank Trial Statement, August 18, Brief of Evidence, 1913; Georgia Supreme Court Brief, 1913, 1914).

Leo Frank Jailhouse Interview:

Leo Frank astonishingly re-confirms he might have been in the men's toilet (only one set of toilets existed on the second floor of the National Pencil Company factory, they are located in the machine department AKA metal room) at the time Monteen Stover said his office had been empty on the murder day (between 12:05 pm to 12:10 pm). This ineluctably incriminating admission was first given by Leo Frank on August 18, 1913, at his trial while he was seated on the witness stand. He once again placed himself at the scene of the crime at the time the sex-murder occurred. You have to read it with your own eyes to believe it.

Source: Atlanta Constitution, Monday, March 9, 1914, Leo Frank Jailhouse Interview
WWW Link: https://archive.org/details/AtlantaConstitutionMondayMarch91914Issue10Pages

U.S. Senator From Georgia Tom Watson:

Tom Watson's Jeffersonian Newspaper about the Leo Frank Case and its principals can be found in some of the weekly issues during 1914, 1915, 1916 and 1917 and in Watson's monthly magazine (1915). Tom Watson's best work on the Leo M. Frank case were published in August and September of 1915 in his Watson's Jeffersonian Magazine.

Watson's five major magazine works written serially on the Frank-Phagan affair, provide logical arguments confirming the guilt of Leo M. Frank with the superb reasoning of a seasoned criminal attorney. These five 1915 articles spread out over numerous months are absolutely required reading for anyone interested in the Leo M. Frank Case. Originals of these magazines are extremely difficult to find because efforts have been ongoing since 1915 to make them disappear. Fortunately, a small number of these issues have survived into the 21st century and they have been digitized so they might last forever.

January 1915: The Leo Frank Case By Tom Watson (January 1915) Watson's Magazine Volume 20 No. 3. See page 139 for the Leo Frank Case. Jeffersonian Publishing Company, Thomson, Ga.
Digital Source: https://archive.org/details/TheLeoFrankCase

March 1915: The Full Review of the Leo Frank Case By Tom Watson (March 1915) Volume 20. No. 5. See page 235 for 'A Full Review of the Leo Frank Case'. Jeffersonian Publishing Company, Thomson, Ga.
Digital Source:
https://archive.org/details/TheFullReviewOfTheLeoFrankCaseMarch1915

August 1915: The Celebrated Case of The State of Georgia vs. Leo Frank By Tom Watson (August 1915) Volumne 21, No 4. See page 182 for 'The Celebrated Case of the State of Georgia vs. Leo Frank". Jeffersonian Publishing Company, Thomson, Ga.
Digital Source: https://archive.org/details/TheCelebratedCaseOfLeoFrank

September 1915: The Official Record in the Case of Leo Frank, Jew Pervert By Tom Watson (September 1915) Volume 21. No. 5. See page 251 for 'The Official Record in the Case of Leo Frank, Jew Pervert'. Jeffersonian Publishing Company, Thomson, Ga.
Digital Source:
https://archive.org/details/TheOfficialRecordInTheCaseOfLeoFrankJewPervertSeptember1915

October 1915: The Rich Jews Indict a State! The Whole South Traduced in the Matter of Leo Frank By Tom Watson (October 1915) Volume 21. No. 6. See page 301. Jeffersonian Publishing Company, Thomson, Ga
Digital Source: https://www.archive.org/details/RichJewsIndictTheStateOfGeorgia

Tom Watson's Jeffersonian Weekly Newspaper

Watson's analysis of the Phagan-Frank case is the controversial forbidden fruit of truth that have been censored and suppressed for more than 100 years by Leo Frank's defenders, except when they mention it for the purpose of mocking and deriding his works.

For a nearly complete selection of Watson's weekly newspaper discussing the case (click here): Tom Watson's Jeffersonian newspaper articles specifically related to the Murder of Mary Phagan and Leo Frank Case. This collection weekly newspapers about the Leo Frank case and it's principals does not include the monthly Watson's Magazine.

WWW Link:
https://archive.org/details/the-jeffersonian-050714-may-07-1914-volume-11-issue-19-pages-01-03-05-09-10

Tom Watson Brown, Grandson of Thomas Edward Watson:

Notes on the Case of Leo M. Frank and its Aftermath by Tom W. Brown, Emery University, Atlanta, Georgia, 1982. Despite being marred by a few errors (including Brown's belief in the Mary Phagan bitemark hoax) this is still overall a good analysis of the Leo Frank Case.
WWW Link:
https://archive.org/details/NotesOnTheCaseOfLeoMaxFrankAndItsAftermath

The Elusive Leo Frank Georgia Supreme Court Archive (Required Reading):

Leo Frank Trial and Appeals Georgia Supreme Court File (1,800 pages).
WWW Link: https://archive.org/details/leo-frank-georgia-supreme-court-case-records-1913-1914